The nervous system of the body is comprised of two separate systems, the central nervous system and the peripheral nervous system. The peripheral nervous system is comprised of the somatic or “voluntary” nervous system and the autonomic or “automatic” nervous system.
The autonomic nervous system is further broken down into the parasympathetic, sympathetic, and enteric nervous systems. Additionally, it is known that the adrenal glands help to support the sympathetic responses of the autonomic nervous system and the enteric nervous system deals exclusively with the gastrointestinal system. With some overlap they each control various autonomic functions of the body through regulation so neurotransmitter releases which affect nervous control
Acetylcholine is a neurotransmitter used by the parasympathetic nervous system, while nor epinephrine is utilized by the sympathetic nervous system. The adrenal glands secrete epinephrine which help to support the sympathetic nervous system. Norepinephrine and epinephrine together with a substance most affected in Parkinson's disease; dopamine, make up a category of hormones known as the catecholamines.
The enteric nervous system exerts tremendous control over the digestive processes of the body, including gastrointestinal blood flow, secretion absorption, and overall breakdown of food. The enteric nervous system contains a significant number of neurons, thought to be as numerous as those found in the central nervous system. The enteric nervous system is comprised of three types of neurons: sensory, motor, and interneurons. While the sensory neurons are able to determine the environment of the lumen including chemical, ph, thermal and mechanical changes within the lumen, the motor neurons, including those to the pancreatic exocrine cells, control digestion and play a major role in the breakdown of food and the ultimate absorption of nutrients.
There are two network of nerve plexuses which constitute the enteric nervous system: the myenteric plexus and the submucous plexus. The two plexuses extend from the esophagus to the anus and thus run almost the entire route of the gastrointestinal system.
The submucous plexus, which is not continuous throughout the gastrointestinal tract, is located in the submucosal layer of the gastrointestinal tract. Its primary function is to assess the luminal activity of the GI system, and therefore exert tremendous control over GI blood flow, secretions into the lumen and absorption rates of such things as nutrients, water, and hormones such as secretin which is secreted into the blood stream as a result of the enteric nervous systems determination of low Ph of the bolus of food entering the small intestine. This further ultimately determines the role of the pancreatic/digestive enzymes.
The myenteric plexus controls digestive motility and is located in between the longitudinal and circular layers of muscle in the tunica muscularis. It is this segment of the enteric nervous system which may be initially affected in Parkinson's disease.
The overall digestive process includes the communication between the autonomic (enteric) nervous system and the central nervous system as digestion does not happen solely as a function of the autonomic nervous system. Additionally, there are significant enteric hormones that affect digestion, including secretin, which are under the control of the autonomic nervous system. From the autonomic nervous system, there is an overall increase in the stimulation of digestion from the parasympathetic branch of the autonomic nervous system which occurs mainly through the secretion of the neurotransmitter acetylcholine, while norepinephrine, secreted by the sympathetic nervous system decreases digestion in the gastrointestinal tract.
Dysautonomias are diseases and syndromes that relate to the autonomic nervous system of the individual. Hence in individuals afflicted with dysautonomias, many normal and automatic functions of the body are left with poor function or little to no function at all.
There are a plethora of dysautonomic disorders in which the symptoms of autonomic dysfunction are manifest. For instance, Parkinson's disease is marked by mild to severe autonomic dysfunction including changes in gait, tremor, discoordination, increased salivary flow, and overall loss of autonomic function. Additionally, changes in executive function are typically noted in a Parkinson's patient, often allowing the patient to appear as having Alzheimer's disease and resulting in misdiagnosis. Executive function disorders are also found in autistic children.
It has been noted that a lack of secretin response, which is directly under the control of the enteric nervous system, may underlie may other conditions. Further, the use of secretin directly as a therapeutic agent may be efficacious as in the case of those with familial dysautonomia.
Parkinson's disease is widespread throughout the Western hemisphere and was first reported by physician James Parkinson in 1817. Parkinson's disease is first detected as a tremor in a limb, and ultimately progresses to include 3 manifestations: (i) rigidity, which is characterized by “cog-wheel” like movement and “lead-pipe” rigidity; (ii) bradykinesia or slowness in movement, and (iii) postural instability associated with a stooped stance and an impaired gait. These altered movements are features of the motor dysfunction, but in addition there can also be a mental impairment in as many as 40% of all Parkinson's patients.
It is known that Parkinson's disease is caused by a deficient state of levo-dopamine in the brain. More specifically, levo-dopa induced dyskinesis in Parkinson's patients is thought to be a result of denervation of the substantia nigra. To date, medical science has not found a substrate that would allow an injectable form of levo-dopa to reach the brain and successfully cross the blood brain barrier. The current dopamine replacement therapy is aimed at either direct replacement or mimicking the action at the dopamine receptor sites in the brain. Sinemet™. and Sinemet CR™ are the two major drugs suited to that end. While the levo-dopa therapy can create some beneficial changes initially, those changes generally wane over time, and produce other problems such as severe sleep disturbance, dyskinesias, and constant nausea. Medical approaches to Parkinson's disease include surgical destruction of the tissue of the brain and the insertion of microelectrodes (deep brain electrical stimulation) to effected portions of the brain. The insertion of electrodes has the advantage of being reversible. These interventions, however, are generally transient and neither produces a permanent change in the Parkinsonian state nor reverses the effects of the disease.
Some authors suggest that Parkinson's disease is a multifactor, neurodegenerative disorder, which evolves due to excessive oxidation. The substantia nigra is susceptible to oxidative damage which supports this theory of the formation of Parkinson's disease. Abnormalities of the oxidative phosphorylation impair the mitochondria of the substantia nigra, and intensify free radical generation.
While the dyskinesias and loss of executive functioning of the brain receive the most significant mention with respect to Parkinson's disease, other physical manifestations exist that are associated with autonomic dysfunction which are often poorly understood. Some of these manifestations include, e.g.: esophageal reflux, diarrhea, and other gastrointestinal dysfunction. In addition, excessive sweating, sleep disturbances and other symptoms of Parkinson's disease are very similar to those found in familial dysautonomia.
It has long been held that protein restricted diets, timed protein intake diets, or low protein diets were essential for the absorption of certain medications, especially levo-dopa, in the patient afflicted with Parkinson's disease. Many studies have demonstrated the possibility that the large neutral amino acids (tryptophan, valine, isoleucine, leucine, tyrosine, phenylalanine) may interfere with the absorption of the 1-dopamine. Numerous studies have been performed and much postulation has been made about various diets. It has long been held by the inventor that there was a decrease in protein digestion in the dysautonomic patient, including those with Parkinson's disease. This lack of protein digestion would therefore necessitate an alteration in the protein intake in individuals with this type of dysfunction, including a decrease in the ingestion of certain proteins which may be difficult to digest without the presence of the necessary digestive enzyme and/or proper functioning of the secretin mechanism, and the over-ingestion of protein to make up for that which is not digested when there in an apparent impairment in protein digestive function. For example, if an individual needed 40 grams of protein a day to sustain function, but had only a mechanism which was 10% effective then the individual would gravitate toward a diet which was higher in protein and protein which would be easier to digest.
This fact has recently been demonstrated in a paper found in Movement Disorders: Protein Intake in Parkinsonian patients using the EPIC food frequency questionnaire by Marczewska on Apr. 18, 2006. In this paper, 45 Parkinson's patients were evaluated using the EPIC food questionnaire. While average caloric intake was normal in the Parkinson's patients, they consumed significantly higher amounts of protein (mainly in the form of vegetable proteins). The overall protein intake was 50% higher than the recommended daily allowance (1.2 g/kg vs. 0.8 g/kg). More importantly, it showed that the more severe the symptoms of the patient, the greater the protein intake by the patient.
Further, chymotrypsin appears to continue to be a biomarker for those with Parkinson's disease as the chymotrypsin cleaves only essential amino acids. If there is a dearth of chymotrypsin, then the essential amino acids needed by the body will not be available, and a greater ingestion of protein may be needed in order to attain sufficient essential amino acids.
Accordingly, in view of such findings, a method for determining whether an individual suffering from a dysautonomic disorder and/or any disorder comprising dysautonomic components will benefit from the administration of secretin, or pancreatic/digestive enzymes, would be highly advantageous. In addition, a method for aiding in the diagnosis of individuals who may develop Parkinson's disease and related conditions or symptoms is highly desirable.